This application is based upon and claims the benefit of priority from the prior Japanese Patent Applications No. 11-200487, filed Jul. 14, 1999; No. 11-200488, filed Jul. 14, 1999; and No. 2000-113571, filed Apr. 14, 2000, the entire contents of which are incorporated herein by reference.
The present invention relates to a carbon fiber-reinforced carbon composite body excellent in oxidation resistance and suitable for use in the manufacture of, particularly, a sliding member in Concorde, a nose cone and a leading edge of a space shuttle, parts of a combustion engine, and medical parts such as an artificial root of tooth, bone and joint, and a method of manufacturing the same.
As widely known, the carbon fiber-reinforced carbon composite body exhibits an excellent mechanical strength under high temperatures and, thus, is expected to provide a material exhibiting a high mechanical strength under high temperatures. However, since the complex body consists of carbon alone, the composite body is oxidized under an oxidizing atmosphere of 500xc2x0 C. or higher, resulting in failure to exhibit its excellent characteristics under very high temperatures.
It was customary in the past to cover the carbon fiber-reinforced carbon composite body with a ceramic material in order to improve the oxidation resistance and resistance to chemicals. The particular technique is disclosed in, for example, Japanese Patent Disclosure (Kokai) No. 8-253371. One of the most popular methods of covering the composite body with the ceramic material is to employ a chemical vapor deposition (CVD) method. The CVD method certainly permits forming a thick ceramic material film. However, it is difficult to apply the CVD method to the carbon fiber-reinforced composite body having an irregular shape.
In recent years, the demands for a carbon fiber-reinforced carbon composite body exhibiting a sufficiently high oxidation resistance are being increased with progress of an international space program.
Also, conventional composite materials with improved oxidation resistance are disclosed in, for example, Japanese Patent Disclosure No. 4-316611 and Japanese Patent Disclosure No. 5-186267.
A first object of the present invention is to provide a carbon fiber-reinforced carbon composite body doped with silicon boride, capable of preventing oxidation under high temperatures not lower than 500xc2x0 C., exhibiting an excellent durability, and applicable to the manufacture of an article having an irregular shape, the carbon fiber-reinforced carbon composite body being hereinafter called a first invention.
A second object of the present invention is to provide a method of manufacturing a carbon fiber-reinforced carbon composite body capable of preventing oxidation under high temperatures not lower than 500xc2x0 C., exhibiting an excellent durability, and applicable to the manufacture of an article having an irregular shape, comprising the steps of covering the surface of a carbon fiber-reinforced carbon composite material with a layer of silicon boride such as SiB4 or SiB6, and applying a hot pressing to the covering layer to permit the inner region of the composite body to be doped with the silicon boride, the method being hereinafter called a second invention.
A third object of the present invention is to provide a carbon fiber-reinforced carbon composite body covered with a surface layer impregnated with silicon boride and exhibiting the effects similar to those exhibited by the first invention, the carbon fiber-reinforced carbon composite body being hereinafter referred to as a third invention.
A fourth object of the present invention is to provide a method of manufacturing a carbon fiber-reinforced carbon composite body exhibiting effects similar to those exhibited by the second invention, comprising the steps of dipping a carbon fiber-reinforced carbon composite body in a suspension prepared by dispersing a powdery silicon boride of SiB4 or SiB6 in an organic dispersing medium to permit the composite body to be impregnated with the silicon boride, and evaporating the organic dispersing medium to form a surface layer impregnated with the silicon boride on the surface of the composite body, the method being hereinafter referred to as a fourth invention.
A fifth object of the present invention is to provide a carbon fiber-reinforced carbon composite body covered with a calcium boride layer forming an oxidation resistant film of CaB4O7 or CaB2O4 during oxidation under high temperatures, and exhibiting an excellent oxidation resistance and an excellent durability, the carbon fiber-reinforced carbon composite body being hereinafter referred to as a fifth invention.
A sixth object of the present invention is to provide a method of manufacturing a carbon fiber-reinforced carbon composite body exhibiting the effects similar to the effects exhibited by the fifth invention, comprising the steps of dipping a carbon fiber-reinforced carbon composite material in a dispersion prepared by dispersing a powdery CaB6 in an organic solvent to permit the carbon composite material to be impregnated with the dispersion, and applying a degreasing treatment to the composite body to form a calcium boride layer on the surface of the composite body, the method being hereinafter referred to as a sixth invention.
A seventh object of the present invention is to provide a method of manufacturing a carbon fiber-reinforced carbon composite body excellent in oxidation resistance and durability and applicable to the manufacture of an article having a complex shape, comprising the steps of setting a carbon fiber-reinforced carbon composite material in a container housing a dispersion prepared by dispersing a calcium boride powder in an organic solvent, and forming a calcium boride layer on at least the surface of the composite material by a cold isostatic press method, the method being hereinafter referred to as a seventh invention.
An eighth object of the present invention is to provide a carbon fiber-reinforced carbon composite body exhibiting the effects similar to those exhibited by the fifth invention, comprising a carbon fiber-reinforced carbon composite material and a calcium boride composite material layer containing a chromium compound and formed on the surface of the carbon composite body, the carbon fiber-reinforced carbon composite body being hereinafter referred to as an eighth invention.
A ninth object of the present invention is to provide a method of manufacturing a carbon fiber-reinforced carbon composite body exhibiting the effects similar to those exhibited by the fifth invention, comprising the steps of dipping a carbon fiber-reinforced carbon composite material containing calcium boride and a chromium compound in a dispersion prepared by dispersing a CaB6 composite material in an organic solvent, and applying a degreasing treatment to form a calcium boride complex layer on the surface of the composite material, the method being hereinafter referred to as a ninth invention.
Further, a tenth object of the present invention is to provide a method of manufacturing a carbon fiber-reinforced carbon composite body exhibiting the effects similar to those exhibited by the seventh invention, comprising the steps of setting a carbon fiber-reinforced carbon composite material in a container housing a dispersion prepared by dispersing a calcium boride complex powder having a chromium compound added thereto, and forming a calcium boride complex layer on at least the surface of the composite material by a cold isostatic press method, the method being hereinafter referred to as a tenth invention.
According to the first invention, there is provided a carbon fiber-reinforced carbon composite body, characterized in that the inner region of the carbon fiber-reinforced carbon composite material is doped with silicon boride.
According to the second invention, there is provided a method of manufacturing a carbon fiber-reinforced carbon composite body, characterized by comprising the steps of forming a covering layer consisting of silicon boride such as SiB4 or SiB6 on the surface of the carbon fiber-reinforced carbon composite material, and doping the inner region of the carbon fiber-reinforced carbon composite body with the silicon boride by applying a hot pressing.
According to the third invention, there is provided a carbon fiber-reinforced carbon composite body, characterized in that a covering layer impregnated with silicon boride is formed on the surface of the carbon fiber-reinforced carbon composite material.
According to the fourth invention, there is provided a method of manufacturing a carbon fiber-reinforced carbon composite body, characterized by comprising the steps of dipping a carbon fiber-reinforced carbon composite material in a dispersion prepared by dispersing a powdery silicon boride of SiB4 or SiB6 in an organic solvent to permit the carbon composite material to be impregnated with silicon boride, and evaporating the organic solvent so as to form a covering layer impregnated with silicon boride on the surface of the carbon composite material.
According to the fifth invention, there is provided a carbon fiber-reinforced carbon composite body, characterized in that a calcium boride layer forming an oxidation resistant film consisting of at least one of CaB4O7 and CaB2O4 during oxidation under high temperatures is formed on at least the surface of the carbon fiber-reinforced carbon composite material.
According to the sixth invention, there is provided a method of manufacturing a carbon fiber-reinforced carbon composite body, characterized by comprising the steps of dipping a carbon fiber-reinforced carbon composite material in a dispersion prepared by dispersing a calcium boride powder in an organic solvent for impregnating the carbon composite material with calcium boride, and applying a degreasing treatment to form a calcium boride layer on the surface of the carbon composite material.
According to the seventh invention, there is provided a method of manufacturing a carbon fiber-reinforced carbon composite body, characterized by comprising the steps of setting a carbon fiber-reinforced carbon composite material in a container housing a dispersion prepared by dispersing a calcium boride powder in an organic solvent, and forming a calcium boride layer on at least the surface of the carbon composite material by a cold isostatic press method.
According to the eighth invention, there is provided a carbon fiber-reinforced carbon composite body, characterized in that a calcium boride complex layer having a chromium compound added thereto is formed on the surface of the carbon fiber-reinforced carbon composite material.
According to the ninth invention, there is provided a method of manufacturing a carbon fiber-reinforced carbon composite body, characterized by comprising the steps of dipping a carbon fiber-reinforced carbon composite material in a dispersion prepared by dispersing a calcium boride composite material having a chromium compound added thereto in an organic solvent, and applying a degreasing treatment to form a calcium boride complex layer having a chromium compound added thereto on the surface of the carbon composite material.
Further, according to the tenth invention, there is provided a method of manufacturing a carbon fiber-reinforced carbon composite body, characterized by comprising the steps of setting a carbon fiber-reinforced carbon composite material in a container housing a dispersion prepared by dispersing a calcium boride composite material having a chromium compound added thereto in an organic solvent, and forming a calcium boride complex layer having a chromium compound added thereto on at least the surface of the carbon composite body by a cold isostatic press method.